In recent years, a marketing product using a packaging container which keeps foods having oil and fat content such as confectionary, retort food, frozen food, processed meat, condiments, and powdered soup as contents, is required to avoid alterations of food tastes and of qualities during a period from producing the marketing product until supplying to customers by retaining the light-blocking properties. Besides the above mentioned, in a packaging container which keeps medical drugs with taking the embodiments such as medicinal solution, medicinal agent, and health drink and moreover, in a packaging container which keeps industrial products such as liquid detergent, shampoo, rinse, and softener, contents are required to avoid alterations by retaining the light-blocking properties.
Also, when displaying the above mentioned various marketing products, representing contents by various kinds of designs on surface of a packaging container so as not to be seen the contents is advantageous to encourage the willingness to buy by customers and at the same time the opacifying properties to a packaging material are also required to retain.
Accordingly, for such packaging container a packaging material having light-blocking properties by laminating a metal foil such as aluminum so that using metal foil is also effective to improve the opacifying properties.
Meanwhile, the above mentioned packaging container is widely and commonly distributed and consumed and mostly faces to be disposed after use as wastes, and in case of a thermal disposal of the packaging container, the fact that metal portion in the packaging material remains as residues in an incinerator, is acknowledged as a problem.
From this point of view, in order to retain light-blocking properties without a use of metal such as aluminum, providing a light-blocking printed layer which is made as an achromatic color in a layer structure of the packaging material has become so as to be tried.
Providing a light-blocking printed layer, accordingly, can be easily conducted by printing during production of the packaging material so that there is a big advantage of no increase in production costs. But in case that a light-blocking printed layer is formed by an all-over printing with the black color which gives a great effect for acquirement of light-blocking and opacifying properties, the color as the packaging container of market product for general customers in the external appearance is hard to be accepted, especially as the color of the packaging container for foods and simultaneously, in case that the all-over printing by the black color is observed in the inside of the packaging container of food, a neatness can not be expected to the state of contents which is surrounded by the black color surface. Also, in case that a light-blocking printed layer is formed by an all-over printing only in the white color, the light-blocking properties of the packaging material provide insufficiency as drawbacks.